This invention relates to sterilization of articles, such as surgical instruments, dental instruments and the like, and, more particularly, to sterilization devices and methods employing fluorocarbon liquids as the sterilization medium.
Sterilization of surgical instruments, dental instruments and the like to destroy a wide variety of microorganisms is mandatory in the health science and service fields. Various sterilization techniques have been employed, including exposing the articles to chemical vapors, such as ethylene oxide, to X-ray radiation, to wet heat and to dry heat. The two most widely used techniques are wet heat by pressurized, saturated steam in an autoclave or the like and dry heat in some form of oven.
Steam autoclave sterilizers are quite bulky and expensive, usually require the use of distilled water, and the steam can cause corrosion (unless a corrosion inhibitor is used) and dulling of cutting edges. Hot air oven sterilizers generally are quite slow in reaching the elevated temperatures required for sterilization, require prior thorough cleaning and drying of the articles to be sterilized to remove any material which may insulate underlying microorganisms or become baked on the surface and, when several articles are to be sterilized at once, require special packaging and/or placement of the articles in the oven to insure uniform sterilization of all the articles.
The use of fluorocarbon liquids for sterilization is disclosed in an article by M. Klein and D. G. Millwood entitled "Rapid Sterilization by Heat Using a Fluorocarbon Vapour as the Heat Transfer Medium", reprinted from Excerpted Medica Interantional Congress Series No. 222, OPHTHALMOLOGY, Proceedings of the XXI International Congress, Mexico, D. F. 8-14 Mar. 1970. Such liquids are substantially chemically and biologically inert, non-flamable, thermally stable and have boiling points at temperatures above that required for sterilization. The liquid is heated to boiling and the vapors are allowed to contact and rapidly heat the articles to be sterilized.
Various sterilization devices employing fluorocarbon liquids as the sterilizing medium have been proposed. For example, Pickstone U.S. Pat. No. 3,579,290 discloses a device in which a fluorocarbon liquid located in the lower portion of a chamber is heated to boiling and surgical instruments or the like are lowered into the vapors above the liquid for sterilization. Najarian et al U.S. Pat. No. 4,259,293 discloses a device including a pressurized heating chamber in which the vapors from a boiling fluorocarbon liquid pass over surgical instruments to be sterilized and a relatively complicated system for recovering vapors expelled from the chamber including several valves for condensing vapors, collecting the condensed vapors and returning the collected liquid to the heating chamber. These devices are quite bulky and require a number of moving parts.